Just a quick comment. It will not hurt to use a fast photocell, such
as a solar cell providing CURRENT into an operation amplifier. This
is the only way you can assess the phosphor decay, which is fairly
fast, and this configuration even provides quite a linear signal. If
you want to get a clean signal from the photocell that will reflect
the frame-repetition rate, and not be "contaminated" by individual
lines in the raster, you just set up a series R, parallel C "RC"
filter with the right lowpass time constant before the event detector
(1K, 0.1 uf is a good start).
Hope this helps.
Bob Emerson
On Sun, 5 Dec 1999, Color and Vision Network wrote:
> From: Alvaro Maximo Pons Moreno <Alvaro.Pons@uv.es>
> Subject: stimulus duration
> To: cvnet@lawton.ewind.com
>
> dear dr. Liu
> We had in the past similar problems with the assesment of a inter-stimulus
> time. The problem with photo cells is the refresh rate of the
> monitor. If the stimulus is short in time, you could have problems
> with the refresh rate of the monitor if the response
> rate photocell is too fast. You must consider a photocell with
> a response time fastest than the stimulus duration but slower
> than the refresh rate of the monitor. If you give me the details
> of the stimulus duration of your experiment and monitor
> I could evaluate if the experimental device we use could be useful
> for you.
>
> Dr. ALvaro Pons
>
>
> --
> ***********************************************
> ponsa
> ***********************************************
>
>